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Topic: 805 Bren Parts Wear Inquiry (Read 2106 times)

Have had my 805 Bren for several months now, have it kitted out the way I want, and really like it a lot. It's right around the 10,000 rounds shot mark, and I'm starting to see some metal erosion wear around the 'standard' sized port hole in the gas tube. The wear doesn't seem to extend down into the diameter of the hole (yet), as it is mostly at the surface where the hole meets the port in the gas block. I assume that this is to be expected, but wondering if this amount of wear is normal at this stage of use? (See Photo). Is there a known/projected life span of this part? If the standard sized hole begins to open up due to this wear, it would begin to approach the diameter of the larger, selectable, factory-made 'foul conditions' gas port setting, causing the action to recoil harder and possibly begin to stress other parts. I (obviously) shoot this weapon a lot so that's why I'm asking. Any opinions out there? Thx in advance.

I've sent the same inquiry to CZ this past week... waiting on a response... so will post it here if I get one...

After ~10,000rds, the only other wear I can see so far is some VERY SLIGHT erosion around the top edge of the piston head (a VERY sharply machined edge from the factory), a round wear mark (finish worn off but no material loss) on the front of the bolt carrier where the back end of the piston rod makes contact during recoil, wear marks (worn finish, and a couple of VERY SMALL dings) on the rear of the bolt carrier around the firing pin head where the hammer face contacts, VERY SLIGHT peening of the coned portion of the firing pin head from hammer contact, and two approx. 1/2" long locations inside the aluminum upper (finish worn off, opposite the ejection port side only) where the BCG rides against it when the action is in motion. Bolt lugs, bolt face, ejector, and extractor all look fine. Bolt lug locking grooves at the chamber look fine as well. I have not disassembled the bolt from the carrier yet, only soaked the entire unit in solvent and then scrubbed, and sprayed with "gun scrubber" type cleaner. The weapon has been FLAWLESS in operation throughout this number of rounds... NO malfunctions, except for two dead primer/powder rounds that didn't pew (I only shoot 5.56). The only other thing I'll add is that the extractor on this weapon shaves quite a bit of brass compared to other platforms I use. Cleaning always leaves a small pile of shavings on the bench, mostly coming out of the fire control group under the hammer and the wide groove in the top of the upper above the BCG (this surprised me a bit). I'll try and post more links to photos of these descriptions as soon as I have some time... and the two links posted in my previous comment are photos of the gas tube port hole wear, and one of the entire weapon... hope they work for you.

Awesome! Thanks for the photos and the narrative! Have you stuck with a specific type of ammo (steel cased or brass, 55gr etc)?

Thanks Z00m

No prob... I've put many different brands (WWB; PMC; SADU; Independence; Armscor; Federal Lake City; Remington; PRVI Partisan; Freedom Munitions; MagTech; etc.) and several types of 5.56 FMJ through it (mostly M193/55gr; SS109/62gr; M855/Green Tip), but all were brass... I don't shoot steel case. My 805 has functioned perfectly without so much as a hiccup with everything I've shot... I will say that accuracy definitely varies widely from brand to brand & type to type. SS109 has had the most consistently tight groups out of the 7in1 twist 11" bbl. @ 100 metres.

CZ-USA : GeeMan- Sorry for the delay, but we wanted to do some digging. Erosion at the gas port is to be expected as round counts climb, and the factory sets an overhaul estimate of 20k rounds, at which point guns in military service would get a full rebuild with fresh springs and replacement of any components showing wear. We'd expect that gas port to survive for some time beyond that during normal use, but at some point it would be prudent to swap in a new one. Thanks!

Personally, I like to overmaintain my weapons, like my vehicles... Even with pitting like that, I'd think the pressure would likely be higher than a new gas selector due with longer hole and lacking that "funnel."

So looks like springs and gas selector wouldn't hurt to replace at 10k rounds (personally, I'd do springs at every 5k), and then barrel likely at every 20k, or keyhole. Really depends on your needs/use for the rifle. My main concern would be unnecessary damage to upper or lower receiver, which is almost certainly more costly than otherwise... That said, you've likely shot your weapon more than 90% of US bren owners out there so sort of uncharted territory, haha.

Thanks for sharing the pics. Very interesting (fb pics worked for me -- didn't try google).

Like you RSR, I also prefer to keep high-wear spare parts for my go-to weapons in my kit, especially uncommon ones like my Bren which would not be readily found in a SHTF scenario as compared to AR/M4 replacement parts ("battlefield pick-ups")... As for the gas pressure being higher now due to the wear around the top of that hole, I really have no way of being sure... but the rifle's action does not exhibit any symptoms of an overly violent recoil when set on the 'standard' position from when it was new... I have compared by firing successive rounds alternating the gas port position from 'standard' to 'foul conditions', and after shooting this rifle so much, can actually still "feel" the additional recoil (not a huge difference, but enough to sense for me) of the BCG when firing in the foul conditions setting... A side note here: changing the gas tube setting after firing several hundred rounds can be difficult if not impossible to accomplish (due to carbon build-up) without using some sort of tool, so I just use the business end of a 5.56 round in the hole, and another to depress the detent gas tube pin if needed... so I would say that the wear is not (yet) causing the standard position to work the BCG as if in the foul conditions mode... as mentioned, my concern was more about excessive/premature wear of the working parts of the action and upper receiver rather than the gas tube itself... in later communications with CZ-USA regarding this issue, I asked the same two questions you posed in your post, as well as about better exploded parts drawings than the one in the owners manual, and received the following from them:

"Give our parts department a call 800-955-4486 ext:335 for detailed information on replacement parts as well as availability. We are working on detailed interactive PDF’s for parts, but at this time the only ones we have (PDF drawings) are for our military rifles, and the parts are not all the same."

My minimum preference is to have a spare gas tube, cam pin, firing pin, firing pin plug, ejector, extractor, and a complete spring kit on hand. BTW, the Google photos show detail of all of the other parts displaying wear for anyone interested: